1. Field of the Invention
The present invention relates to a bumper beam and a bumper system for a vehicle.
2. Background Art
Japanese Patent Applications Laid-open No. Toku-Kai-Hei 5-178144 or No. Toku-Kai-Hei 5-278537 disclose vehicular bumper beams formed by extruded material of aluminum. FIG. 8 is a schematic view showing the construction of an example of these bumper beams. This bumper beam 70 is formed by a plurality of box-like closed cross sections 72 and every wall constituting the bumper beam 70 has a uniform wall thickness T. In an event of collision, the impact load inputted from the front of the vehicle is absorbed by the buckling deformation of wall sections of the bumper beam 70.
However, in an actual collision, the vehicle does not always take a desirable attitude for impact absorption. Further, the input direction of impact energy differs in every specific event of collision. Therefore, in some case of collision, the buckling deformation is inadequate and rather, for example, the bumper beam is deformed to a rhomboid configuration. This inadequate buckling deformation makes it difficult to absorb the impact energy efficiently.